1. Field of the Invention
The present invention is directed to fluid delivery systems, and more particularly to surface mount fluid delivery systems for use in the semiconductor processing and petrochemical industries.
2. Discussion of the Related Art
Fluid delivery systems are used in many modern industrial processes for conditioning and manipulating fluid flows to provide controlled admittance of desired substances into the processes. Practitioners have developed an entire class of fluid delivery systems which have fluid handling components removably attached to flow substrates containing fluid pathway conduits. The arrangement of such flow substrates establishes the flow sequence by which the fluid handling components provide the desired fluid conditioning and control. The interface between such flow substrates and removable fluid handling components is standardized and of few variations. Such fluid delivery system designs are often described as modular or surface mount systems. Representative applications of surface mount fluid delivery systems include gas panels used in semiconductor manufacturing equipment and sampling systems used in petrochemical refining. The many types of manufacturing equipment used to perform process steps making semiconductors are collectively referred to as tools. Embodiments of the present invention relate generally to fluid delivery systems for semiconductor processing and specifically to surface mount fluid delivery systems. Aspects of the present invention are applicable to surface mount fluid delivery system designs whether of a localized nature or distributed around a semiconductor processing tool.
Industrial process fluid delivery systems have fluid pathway conduits fabricated from a material chosen according to its mechanical properties and considerations of potential chemical interaction with the fluid being delivered. Stainless steels are commonly chosen for corrosion resistance and robustness, but aluminum or brass may be suitable in some situations where cost and ease of fabrication are of greater concern. Fluid pathways may also be constructed from polymer materials in applications where possible ionic contamination of the fluid would preclude using metals. The method of sealingly joining the fluid handling components to the flow substrate fluid pathway conduits is usually standardized within a particular surface mount system design in order to minimize the number of distinct part types. Most joining methods use a deformable gasket interposed between the fluid component and the flow substrate to which it is attached. Gaskets may be simple elastomeric O-Rings or specialized metal sealing rings such as seen in U.S. Pat. No. 5,803,507 and U.S. Pat. No. 6,357,760. Providing controlled delivery of high purity fluids in semiconductor manufacturing equipment has been of concern since the beginning of the semiconductor electronics industry and the construction of fluid delivery systems using mostly metallic seals was an early development. One early example of a suitable bellows sealed valve is seen in U.S. Pat. No. 3,278,156, while the widely used VCR® fitting for joining fluid conduits is seen in U.S. Pat. No. 3,521,910, and a typical early diaphragm sealed valve is seen in U.S. Pat. No. 5,730,423 for example. The recent commercial interest in photovoltaic solar cell fabrication, which has less stringent purity requirements than needed for making the newest microprocessor devices, may bring a return to fluid delivery systems using elastomeric seals.
A collection of fluid handling components assembled into a sequence intended for handling a single fluid species is frequently referred to as a gas stick. The equipment subsystem comprised of several gas sticks intended to deliver process fluid to a particular semiconductor processing chamber is often called a gas panel. During the 1990s several inventors attacked problems of gas panel maintainability and size by creating gas sticks wherein the general fluid flow path is comprised of passive metallic structures, containing the conduits through which process fluid moves, with valves and like active (and passive) fluid handling components removably attached thereto. The passive fluid flow path elements have been variously called manifolds, substrates, blocks, and the like, with some inconsistency even within the work of individual inventors. This disclosure chooses to use the terminology flow substrate to indicate fluid delivery system elements which contain passive fluid flow path(s) that may have other fluid handling devices mounted there upon.
Many semiconductor manufacturing processes have fluid delivery requirements amenable to quite regular gas panel designs. Such gas panels are comprised of several nearly identical gas sticks conducting fluid in a generally longitudinal direction, from stick inlet to stick outlet, the sticks differing mainly with regard to particular fluid species, flow rates, and such other matters. Selectively chosen transverse connections between gas sticks are used to combine fluid flows for delivery to the processing chamber, or provide purging and vacuum connections, or similar functions known in the art. A process equipment manufacturing environment having recurring need for large quantities, but relatively few types, of gas sticks gives rise to a material management concept sometimes referred to as “standard stick” designs. Embodiments of the present invention are directed to lower cost flow substrate and standard stick bracket designs which enhance the ease of installing, or replacing, complete gas stick subassemblies in a gas panel subsystem while making standard stick designs less expensive.
Some examples of regularized gas panels are described in U.S. Pat. No. 5,836,355, U.S. Pat. No. 6,283,155, and U.S. Pat. No. 6,302,141 wherein the component bearing substrate block parts have component ports on one surface, and one or more manifold ports on the opposite surface, whereby transverse connection between gas sticks is provided through a second lower layer of block parts in sealing registration with the manifold port(s). In these designs it is not feasible to remove a single gas stick intact from the gas panel because one or more active components must first be removed to allow access to the fasteners which couple together the first and second layers of substrate blocks. A similar problem exists in the gas stick of U.S. Pat. No. 6,769,463 which uses a welded assembly of fluid conduits to provide the transverse connecting second layer instead of a bolted assembly of blocks.
U.S. Pat. No. 5,992,463 describes a regularized gas panel wherein the component bearing manifold (substrate) parts have all fluid ports only in a common plane whereby transverse connection between gas sticks is provided through bridging components directly attached to ports in that common plane as described in U.S. Pat. No. 6,435,215. Replacement of a gas stick requires removal of the appropriate bridging component(s) but does not necessitate disruption of the gas stick itself. Similar use of bridging components may be seen in U.S. Pat. No. 6,293,310, U.S. Pat. No. 6,374,859, and U.S. Pat. No. 6,394,138 for example.